The present invention relates generally to induction heating, and particularly to a method and apparatus for inductively heating a workpiece using a flexible fluid-cooled induction heating cable.
Resistive heating is a method of heating a workpiece by flowing electrical current through a resistive heating element. The temperature of the resistive heating element rises due to the flow of electric current through the resistive heating element. Heat is transferred from the resistive heating element to the workpiece by a method of heat transfer, such as thermal conduction. By contrast, induction heating is a method of heating a workpiece by using a magnetic field to induce electric currents in the workpiece. The electric currents in the workpiece cause the temperature of the workpiece to rise.
Induction heating involves applying an AC electric signal to a heating loop or coil placed near a specific location on or around an object, such as a metal, to be heated. The varying or alternating current in the loop creates a varying magnetic flux. Electrical currents are induced in the object by the magnetic flux. The object is heated by the flow of electricity induced in the object by the alternating magnetic field. Induction heating may be used for many different purposes, such as pre-heating a metal before welding, post-heating a weld joint, stress relieving a weld joint, annealing, surface hardening, etc.
Electrical conductors within an induction heating cable may serve as the loop or coil to produce the magnetic field. A source of electrical power is coupled to the induction heating cable to produce the magnetic field. However, in contrast to a resistive heating element, it is not desirable to heat the induction heating cable with the flow of electricity through the induction heating cable. Additionally, the high temperatures that a workpiece may experience during induction heating could damage or destroy an induction heating cable. Consequently, fluid-cooled induction heating cables have been developed to remove heat from the induction heating cable. Cooling units are used to pump cooling fluid through the induction heating cable to remove heat.
Current induction heating cables utilize a single integral connector located at each end of the induction heating cable to both fluidicly and electrically couple the induction heating cable to a coolant source and a current source. Additionally, the single connector is threaded to a corresponding connector to complete the electrical and fluidic coupling. However, the single integral connector design is complicated and difficult to manufacture. Additionally, securing each connector to an opposing connector is time consuming and requires tools to complete.
There is a need therefore for a fluid-cooled induction heating cable that avoids the problems associated with an integral electric and fluidic connector. Specifically, there is a need for a fluid-cooled induction heating cable that physically separates the portions of the induction heating cable that are used to electrically couple the induction heating cable to a source of electrical current from those portions of the induction heating cable that are used to fluidicly couple the induction heating cable to a source of cooling fluid. Additionally, there is a need for a connector assembly for a fluid-cooled induction heating cable that is easy to assemble and which can be quickly connected and disconnected without the use of tools.
The present technique provides novel inductive heating components, systems, and methods designed to respond to such needs. According to one aspect of the present technique, an induction heating system is provided. The induction heating system provides a power source and a fluid cooling unit that is operable to provide a flow of cooling fluid. The system also comprises a flexible fluid-cooled induction heating cable that is operable to be electrically coupled to the power source and fluidicly coupled to the fluid cooling unit. The flexible fluid-cooled induction heating cable has a litz wire disposed within a hollow interior of the fluid-cooled induction heating cable. The litz wire is electrically coupled to a plurality of electrical connectors. Each electrical connector is adapted to matingly engage a corresponding electrical connector that is electrically coupled to the power source. The flexible fluid-cooled induction cable also has a plurality of fluid connectors. The fluid connectors are fluidicly coupled to the hollow interior of the fluid-cooled induction heating cable. Each fluid connector is adapted to matingly engage a corresponding fluid connector that is fluidicly coupled to the fluid cooling unit. Each fluid connector also is separate from each electrical connector.
In another arrangement, an induction heating system is provided that comprises a power source, a cooling unit operable to remove heat from a cooling fluid and a flexible induction heating cable. The induction heating cable has an electrical conductor disposed within a hollow interior of the induction heating cable. The induction heating cable has a first electrical connector that is electrically coupled to the electrical conductor. The first electrical connector is adapted for locking engagement with a second electrical connector that is electrically coupled to the power source. The induction heating cable also comprises a first quick-disconnect fluid connector that is fluidicly coupled to the hollow interior of the induction heating cable.
In yet another arrangement, an induction heating system is provided that comprises a power source, a cooling unit, a flexible fluid-cooled induction heating cable, an extension cable, and a first fluid hose. The cooling unit is operable to circulate cooling fluid through the induction heating system. The flexible fluid-cooled induction heating cable has an electrical conductor that is disposed within a hollow interior of the induction heating cable. The flexible induction heating cable also has a first electrical connector that is electrically coupled to the electrical conductor. The flexible fluid-cooled induction heating cable also has a first fluid connector fluidicly coupled to the hollow interior of the flexible fluid-cooled induction heating cable. The extension cable is operable to convey cooling fluid and conduct electricity to the fluid-cooled induction heating cable. The extension cable has a second fluid connector. The first fluid hose is adapted to fluidicly couple the first fluid connector to the second fluid connector.
According to another aspect of the present technique, a fluid-cooled induction heating cable is provided. The fluid-cooled induction heating cable is flexible. The fluid-cooled induction heating cable has a litz wire disposed within a hollow interior of the fluid-cooled induction heating cable. The cable also has a first and a second electrical connector. Each of the electrical connectors is electrically coupled to the litz wire. The cable also has a first and a second fluid connector. Each fluid connector is separate from each electrical connector and fluidicly coupled to the hollow interior of the fluid-cooled induction heating cable.
In another implementation, the induction heating cable has an electrical conductor disposed within a hollow interior of the induction heating cable. The heating cable also has a first electrical connector that is electrically coupled to the electrical conductor. The first electrical connector is adapted for locking engagement with a second electrical connector that is electrically coupled to the power source. The heating cable also has a first quick-disconnect fluid connector that is fluidicly coupled to the hollow interior of the induction heating cable to enable cooling fluid to flow through the hollow interior of the induction heating cable. The induction heating cable is flexible so as to enable the induction heating cable to be wrapped around a pipe.
The extension cable may be formed as an extension cable having a litz wire disposed within a hollow interior of the extension. The extension cable also has a first electrical connector that is electrically coupled to the litz wire. The first electrical connected is adapted to matingly engage a second electrical connector on the fluid-cooled induction heating cable. The extension also has a first fluid connector fluidicly coupled to the hollow interior of the extension. The first fluid connector is adapted to be fluidicly coupled by a jumper hose to a second fluid connector on the fluid-cooled induction heating cable.
An insulation blanket, comprising a mat of silica fiber insulation within a woven silica blanket also is provided. The insulation blanket is adapted for use with a workpiece of a specific size and shape.
The present technique also provides a method of inductively heating a workpiece is provided. The method comprises placing a temperature feedback device on the workpiece and disposing an insulation blanket around a portion of the workpiece to be heated. The method also comprises routing a flexible fluid-cooled induction heating cable over the insulation blanket around the portion of the workpiece to be heated. The method also comprises connecting electrical connectors located at opposite ends of the flexible fluid-cooled induction heating cable to opposing electrical connectors electrically coupleable to an electrical power source. The method also comprises coupling fluid connectors located apart from each electrical connector on the flexible fluid-cooled induction heating cable to fluid hoses. Each fluid connector is coupled to each fluid hose separately from each electrical connector being connected to an opposing electrical connector.